Chaeles b



(No Model.)

ONE. SORIBNER.

CONDENSER im TEST CIRCUIT FOR MULTIPLE SWITCH BOARDS. No. 292,865. Patented Feb. 5, 1884.

/III.

UNITED STATES Parnar FFICE@ CHARLES E. SCRIBNER, OF CHICAGO, ILLINOIS, ASSIGNQR TO THE WESTERN ELECTRIC COMPANY, OF SAME PLACE.

CONDENSER AND TEST-C|RCU|T FOR MULTIPLE SWITCH-BOARDS.

SPECIFICATION forming part of Letters Patent No. 292,865, dated February 5, 1884.

Application filed June 11, 1883. (No model.)

To all whom it may concern! Be it known that I, CHARLES E. SCRIBNER,

a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Condensers and Test Circuits for Multiple Switch-Boards, of which the following is a full, clear, concise, and exact description, reference being had to the ac 1o companying drawings, forming a part of this specification.

My invention herein relates tocondensers and test-circuits for multiple switch-boards of a telephone-exchange; and it consists of a con- .1 denser placed in the circuit of the different pairs of connecting-cords and testing apparatus at the difi'erent boards and circuits, as herein described and claimed.

In the drawingsfwhichare illustrative of my invention, Figure 1 is a diagram of two telephone'linesconnecting with three multiple switch-boards and a pair of connectingcorcls, including a condenser and testing apparatus at each board. The operators out- I fitconsisting of the usual telephone, transmitter, generator or calling battery, and bellis not shown, its construction and use being too well known to require description. Fig. 2 is a detailed view of the loop-plug which I use with my testing apparatus. Fig. 3 is a detailed view of my plug for terminals of the pairs of conducting-cords. The shank of the plug, with the exception of the point, ,is provided with a rubber sleeve, which insulates the plug from the frame of switch. The insulating material being removed from the por-. tion of the point which comes against the spring of the switch, contact is closed between the plug-point and the spring when the plug is inserted.

The circuit of telephone-line 1 may be traced from the subscribers officeto the spring a of the switch upon board A, thence through the contact-point of said switch to a switch upon board 13, and so on to the last board, and

the lines will be disconnected from the last board or succeeding boards. Lines thus connected are open at the condenser bto batterycurrents, but closed to voicecurrents, since, as is well known, voice-currents are readily transmitted through a condenser. Suppose, now, line 2 should be asked for at board A.- The operator, by inserting loop plug 0 in switch d of said line, loops into the circuit of: the two lines the belle and battery f of his testing apparatus. Since the lines, when connected, are open to battery-currents at the condenser b, no current will be sent through the bell e from battery f. The bell, therefore, not ringing, the switchman' at board A will know that line 2 is in use.

The clearing-out annunciator in the circuit with a condenser may be operated by reversed currents sent by a magneto-generator.

Since lines in use on one board are cut off from all succeeding boards, it is obvious that it is unnecessary to make the preliminary test at the last board to ascertain whether a line called for is in use. If the line is found open when the calling-battery is thrown upon it, the operator will know that the line isin use at some one of the preceding boards, and, the line being open, there will be no danger of confusion arising from connections made at any board succeeding the one where the line is connected with another. So

The batteries in the test-circuits at the different boards should not be of sufficient force to throw down the individual annunciator in a line. I introduce sufficient resistance into the bells of the different test-circuits, so that there may be no danger of trouble from the current sent to line from a testing-battery when no condenser is included in its circuitthat is, when the line is not in use.

I claiml. The combination, in amultiple system of switch-boards, of pairs of conducting-cords and condensers, a condenser being in the circuit of each pair of cords, and testing appaterial, said plug being adapted to be inserted .in said switch, whereby said spring is lifted telephone-lines, substantially as and for the IO from said 111g or contact-point and connected purpose specified. to the point of the plug, substantially as and In witness whereof I hereunto subscribe my for the purpose specified. name this 7th day of J une, A. D. 1883.

3. The combination with two connected T 4 telephone-lines, with a condenser in circuitat CHARLES SGRIBL the central office, of a testing-circuit containing a battery and signaling device adapted to be looped into the circuit of the connected 1 Witnesses:

PAUL A. STALEY, G. P. BARTON. 

